1. Field of the Invention
The invention relates to a method for manufacturing suction valve discs and discharge valve discs of fluid displacement apparatus, and in particular, to a method for manufacturing a set of suction valve discs and discharge valve discs for a reciprocating piston-type refrigerant compressor used in an automotive air conditioning system.
2. Description of Related Art
Reciprocating piston-type refrigerant compressors are known in the art. The refrigerant compressor includes a compressor housing defining a compression chamber in which successive piston strokes cause intake, compression, and discharge of a refrigerant gas, and such combination of strokes are repeatedly performed. Further, the compressor may include valve plates positioned at front and rear sides of cylinder block, which partition the compression chamber from the discharge chambers and the suction chambers. A suction valve disc and a discharge valve disc are mounted on both end surfaces of the front and rear valve plates. The valve plate has suction holes and discharge holes extending therethrough to allow communication between the compression chambers and the suction chambers and between the compression chamber and the discharge chamber. Suction valve discs and discharge valve discs, which are made of a resilient material, for example, a carbon steel having a thickness of about 0.3 mm, regulate the flow of the refrigerant gas and sealing engage the end surface of the valve plate when the operation of the compressor ceases.
FIG. 1a depicts an example of a suction valve disc, and FIG. 1b depicts an example of a discharge valve disc, made by a known method. Referring to FIG. 1a, within a large circular valve disc 55', several through-holes 55b, 55c, and 55d are stamp-cut. A plurality of equi-angularly spaced through-holes 55b are the passage holes for fixing bolts. A plurality of equi-angularly spaced, arch-shaped, through-holes 55c form valve reeds 55e. Thus, within this circular suction valve disc, outwardly projecting valve reeds 55e are formed. Further, a plurality of equiangularly spaced through holes 55d are located within base portions of each of valve reeds 55e, described above, allowing the passage of refrigerant from compression chamber into discharge chamber. Referring to FIG. 1b, a discharge valve disc 52 is depicted, which is substantially star-shaped having the same number of outwardly projected reed valve reeds 52b as valve reeds 55e in the suction valve disc 55', described above, and a central through-hole 52a for receiving a fixing bolt.
FIGS. 2a-c illustrate the method for manufacturing one suction valve disc according to the prior art. A detailed description of the steps of this method is as follows:
first, with reference to FIG. 2a, a square material sheet S1 is prepared; PA1 second, with reference to FIG. 2b, various inner through-holes, 55b and 55d and arch-shaped openings 55c are stamped out; and PA1 third, with reference to FIG. 2c, outer edge 55f is stamped out to obtain the complete suction valve disc 55'. PA1 first, with reference to FIG. 3a, a square material sheet S2 is prepared, which is separate from the above-mentioned sheet S1 used for producing a suction valve disc; PA1 second, with reference to FIG. 3b, a central through hole 52a is stamped out; and PA1 with reference to FIG. 3c, an outer edge 52c is stamped out to obtain the complete discharge valve disc 52.
FIGS. 3a-c illustrate the method for manufacturing one discharge valve disc according to the prior art. A detailed description of the steps of this method is as follows:
Thus, known methods for manufacturing suction valve and discharge valve discs consume two separate material sheets S1 and S2, one for each kind of valve disc, giving rise to a significantly increased cost for the product. Moreover, in manufacturing methods for sets of suction valve and discharge valve discs, the material cost is a significant component. Therefore, it is desirable to reduce this material cost.